Pesticides for Stored Products
247
9.4. AL TERN A TIVE CHEMICAL CONTROL TECHNIQUES
Up to this point, I have discussed the use of insecticidal compounds-the
fumigants and grain protectants. These conventional techniques may be supplemented by good hygiene and physical methods of insect control (e.g., inert
atmospheres, specially designed storage facilities, infrasound treatment, gamma
radiation, microwaves) or by newer chemical methods.
Insecticidal residues and the onset of insect resistance are two major problems associated with excessive reliance upon a limited number of chemical
insecticides. In all aspects of insect control, it is important to use pesticides
wisely, and any decision to use a pesticide should be based on a knowledge of
the type and extent of infestation and the economic or other benefit to be expected
from the treatment. Many more alternatives must be provided for the user, who
is at present limited to a very restricted range of approved treatments. It is the
obligation of the research scientist to explore the whole range of possible strategies that might be used in the control of insect pests.
Consideration of the physiology and biochemistry of the insect provides us
with many potential sites at which chemical intervention might initiate a chain
of events that could result in death or in failure to develop or reproduce. In an
excellent review, Levinson (1975) discusses the potential application of insectistatics and pheromones in insect pest control, particularly with regard to the
problem of stored-product insects. It is worthwhile to summarize its conclusions,
because the author's approach is based on the physiology of the insect and
explores the possibilities of utilizing agents that interfere with the normal function
of physiologically active compounds. Some of these compounds are now in
experimental use, others represent only hypothetical possibilities for utilization.
Levinson uses the term insectistatics because most such agents affect growth and
reproduction rather than having a direct insecticidal effect. He suggests that
sublethal levels may be sufficient to exert control, which means we could avoid
the problem of the rapid development of resistant species. The following approaches are suggested:
1. Compounds that affect the integument. Inhibition of the pathway of
chitin biosynthesis is a promising method of reducing the survival rate
of developing insects. A number of antagonists of chitin biosynthesis,
of several structural types, are known. One of the most effective of these
is the recently introduced compound diftubenzuron, N-([(4-chlorophenyl)amino]-carbonyl)2,6-diftuorobenzamide, an insecticide which may
have wide application. Such compounds might be effectively utilized
against stored-product insects by formulation in baits.
2. Compounds that affect hormone balance. Applications of compounds
that have hormonelike activity are being explored. Such compounds are
247
9.4. AL TERN A TIVE CHEMICAL CONTROL TECHNIQUES
Up to this point, I have discussed the use of insecticidal compounds-the
fumigants and grain protectants. These conventional techniques may be supplemented by good hygiene and physical methods of insect control (e.g., inert
atmospheres, specially designed storage facilities, infrasound treatment, gamma
radiation, microwaves) or by newer chemical methods.
Insecticidal residues and the onset of insect resistance are two major problems associated with excessive reliance upon a limited number of chemical
insecticides. In all aspects of insect control, it is important to use pesticides
wisely, and any decision to use a pesticide should be based on a knowledge of
the type and extent of infestation and the economic or other benefit to be expected
from the treatment. Many more alternatives must be provided for the user, who
is at present limited to a very restricted range of approved treatments. It is the
obligation of the research scientist to explore the whole range of possible strategies that might be used in the control of insect pests.
Consideration of the physiology and biochemistry of the insect provides us
with many potential sites at which chemical intervention might initiate a chain
of events that could result in death or in failure to develop or reproduce. In an
excellent review, Levinson (1975) discusses the potential application of insectistatics and pheromones in insect pest control, particularly with regard to the
problem of stored-product insects. It is worthwhile to summarize its conclusions,
because the author's approach is based on the physiology of the insect and
explores the possibilities of utilizing agents that interfere with the normal function
of physiologically active compounds. Some of these compounds are now in
experimental use, others represent only hypothetical possibilities for utilization.
Levinson uses the term insectistatics because most such agents affect growth and
reproduction rather than having a direct insecticidal effect. He suggests that
sublethal levels may be sufficient to exert control, which means we could avoid
the problem of the rapid development of resistant species. The following approaches are suggested:
1. Compounds that affect the integument. Inhibition of the pathway of
chitin biosynthesis is a promising method of reducing the survival rate
of developing insects. A number of antagonists of chitin biosynthesis,
of several structural types, are known. One of the most effective of these
is the recently introduced compound diftubenzuron, N-([(4-chlorophenyl)amino]-carbonyl)2,6-diftuorobenzamide, an insecticide which may
have wide application. Such compounds might be effectively utilized
against stored-product insects by formulation in baits.
2. Compounds that affect hormone balance. Applications of compounds
that have hormonelike activity are being explored. Such compounds are